How Does 3D TV Work?
How does 3D TV work? More and more consumers are asking this question as the 3D technology has gone mainstream. Over the past few years, there has been a significant rise in the number of 3D televisions introduced to the market.
Manufacturers are competing with each other to develop the best 3D television technology that will be accepted by consumers. Here is some information that will help you understand how the 3D TV works.
How We See in 3D
3D television viewing is modelled on the basis of 3D perception in humans, which is a result of binocular vision, i.e. vision in which the two eyes are used together.
In normal viewing, the two eyes perceive slightly different images, which are merged by the brain to form images capable of providing perception of depth.
3D display technology created for televisions has to be able to trick a viewer’s eyes to believe that the images being viewed have 3 dimensions. 3D television manufacturers use innovative techniques to achieve this effect.
Fundamentally, these technologies should have the capacity to transmit slightly different images to the two eyes. When this happens, the brain processes the two images and forms a 3D perception. The main types of 3D technology employed for commercial use are: anaglyph 3D, polarized 3D, active 3D and lenticular technology.
How Does 3D TV Work with Anaglyph Technology?
Wilhelm Rollman developed the anaglyph technique way back in 1853. It was later employed to design colour filtered glasses for viewing 3D movies in theatres. Each lens of these 3D glasses is of a different colour and they are paired such that the lens colour of one is chromatically opposite to the other. The most common colour pair for these lenses is red and blue.
The image generated on the screen by the TV is composed of two images slightly overlapping each other. Each of these images is filtered with a different colour. One anaglyph filter takes in red light from the screen and sends it to the eye as white colour, while the blue parts of the image are darkened. The other lens functions in exactly the opposite manner.
This way, the eye behind the blue lens will perceive only red images and those behind red will perceive only blue ones. Each eye sees only one image and the brain assumes that both eyes are viewing the same image, creating an illusion of depth.
These 3D glasses have a number of drawbacks as a result of which they haven’t gained much popularity with consumers. One such drawback is that as the lenses are tinted with a particular colour; the images created by them have low colour fidelity and generally just have shades of red and blue.
How Does 3D TV Work with Polarization Technique?
3D TVs employing polarization are used with polarized glasses, whose lenses filter light waves that are polarized in a specific direction.
Only light polarized in a way compatible with either lens is allowed through each of them, as a result of which, each eye perceives only one set of images. The images are then processed by the brain in the same manner as it does for real life images.
One advantage of polarized glasses is that image details and colours shown by them are similar to that of real life 3D content. Polarized glasses offer viewing experience that is among the best in different 3D technologies. Another advantage of using these glasses is that they are relatively cost effective as they make use of passive technology.
With polarized glasses, users can also conveniently shift between 2D and 3D viewing experiences. However, even these lenses have drawbacks, especially if they are used for viewing at home.
The television screen has to be coated with a special polarization film prior to using it and this is an inconvenience for many people. That is why most 3D television manufacturers refrain from employing this technology in their televisions.
How Does 3D TV Work with Active Technology?
In the recent past, television manufacturers have developed 3D technology that does not employ coloured lenses or polarization films. The eyewear used has infrared sensors with which it connects wirelessly to a 3D LCD TV or 3D LED TV. When the screen shows 3D content, it alternates between two versions of an image.
In active technology, however, the two image versions are not displayed at the same time, and there is a tiny lag between the two images. When the images alternate on the screen, the glass lenses alternate between being opaque and transparent. So when the right eye receives input for an image shown on screen, the left eye does not receive any input.
This happens at a very high speed, as a result of which the brain does not have time to perceive a flicker in the images. As the closing and opening is timed in sync with on-screen images, each eye views only one version of the image. A stereoscopic sync connector is plugged into an infrared (IR) emitter. This emitter transmits signals to the 3D glasses using active lenses. This helps the lens synchronize with 3D content on screen.
Manufacturers have started incorporating this technology in their television units only recently. This is because most of the older plasma and LCD television models had low refresh rates as a result of which this technology could not be employed in them.
Refresh rate is the speed with which a screen replaces images and when this is low, the viewers will be able to detect a flicker when they use these glasses. But in most of the latest television models, the refresh rates are high and viewers can enjoy a great 3D experience.
3D TV Without Glasses
3D television technology has improved drastically in the last few years. One area that is rapidly undergoing improvements is the ability to get rid of special eyewear.
A large number of consumers are demanding TVs capable of providing 3D images without the use of glasses, and there have already been some significant strides in this direction.
So how does 3D TV work without glasses? One method enabling 3D eyewear free viewing employs lenticules, which are small lenses located at the base of a special film. This film is used on a display which has the ability to generate two versions of the same image. The lenticules then send light from the screen to the viewer’s eyes such that each eye receives a slightly different image. The brain processes these images such that they are interpreted as a single three dimensional image.
One disadvantage of the current lenticular technology is that the viewer will have to be within a certain distance of the screen to experience its 3D effect. When the viewer moves away from the screen, the images will blur and return to 2D. There are several other technologies that are currently being developed or tested to provide 3D experience without requiring glasses, and some of them will mature over the next few years.
